Computation of the electronic flux density in the Born-Oppenheimer approximation.

A molecule in the electronic ground state described in the Born­Oppenheimer approximation (BOA) by the wave function ΨBO = Φ0χ0 (where Φ0 is the time-independent electronic energy eigenfunction and χ0 is a time-dependent nuclear wave packet) exhibits a nonzero nuclear flux density, whereas it always displays zero electronic flux density (EFD), because the electrons are in a stationary state. A hierarchical approach to the computation of the EFD within the context of the BOA, which utilizes only standard techniques of quantum chemistry (to obtain Φ0) and quantum dynamics (to describe the evolution of χ0 on the ground-state potential energy surface), provides a resolution of this puzzling, nonintuitive result. The procedure is applied to H2(+) oriented parallel with the z-axis and vibrating in the ground state (2)Σg(+). First, Φ0 and χ0 are combined by the coupled-channels technique to give the normally dominant z-component of the EFD. Imposition of the constraints of electronic continuity, cylindrical symmetry of Φ0 and two boundary conditions on the EFD through a scaling procedure yields an improved z-component, which is then used to compute the complementary orthogonal ρ-component. The resulting EFD agrees with its highly accurate counterpart furnished by a non-BOA treatment of the system.

Differentiation expression during proliferative activity induced through different pathways: in situ hybridization study of thyroglobulin gene expression in thyroid epithelial cells.

In canine thyrocytes in primary culture, our previous studies have identified three mitogenic agents and pathways: thyrotropin (TSH) acting through cyclic AMP (cAMP), EGF and its receptor tyrosine protein kinase, and the phorbol esters that stimulate protein kinase C. TSH enhances, while EGF and phorbol esters inhibit, the expression of differentiation. Given that growth and differentiation expression are often considered as mutually exclusive activities of the cells, it was conceivable that the differentiating action of TSH was restricted to noncycling (Go) cells, while the inhibition of the differentiation expression by EGF and phorbol esters only concerned proliferating cells. Therefore, the capacity to express the thyroglobulin (Tg) gene, the most prominent marker of differentiation in thyrocytes, was studied in proliferative cells (with insulin) and in quiescent cells (without insulin). Using cRNA in situ hybridization, we observed that TSH (and, to a lesser extent, insulin and insulin-like growth factor I) restored or maintained the expression of the Tg gene. Without these hormones, the Tg mRNA content became undetectable in most of the cells. EGF and 12-0-tetradecanoyl phorbol-13-acetate (TPA) inhibited the Tg mRNA accumulation induced by TSH (and/or insulin). Most of the cells (up to 90%) responded to both TSH and EGF. Nevertheless, the range of individual response was quite variable. The effects of TSH and EGF on differentiation expression were not dependent on insulin and can therefore be dissociated from their mitogenic effects. Cell cycling did not affect the induction of Tg gene. Indeed, the same cell distribution of Tg mRNA content was observed in quiescent cells stimulated by TSH alone, or in cells approximately 50% of which had performed one mitotic cycle in response to TSH + insulin. Moreover, after proliferation in "dedifferentiating" conditions (EGF + serum + insulin), thyrocytes had acquired a fusiform fibroblast-like morphology, and responded to TSH by regaining a characteristic epithelial shape and high Tg mRNA content. 32 h after the replacement of EGF by TSH, cells in mitosis presented the same distribution of the Tg mRNA content as the rest of the cell population. This implies that cell cycling (at least 27 h, as previously shown) did not affect the induction of the Tg gene which is clearly detectable after a time lag of at least 24 h. The data unequivocally show that the reexpression of differentiation and proliferative activity are separate but fully compatible processes when induced by cAMP in thyrocytes.(ABSTRACT TRUNCATED AT 400 WORDS)

Manejo de la Diverticulitis Apendicular: una patología poco común

La diverticulitis apendicular es una enfermedad poco frecuente, con una incidencia aproximada de 1%. Se define por la presencia de divertículos verdaderos o falsos en la pared del apéndice cecal. Durante la fase aguda posee una clínica indistinguible a la apendicitis, sin embargo en ocasiones presenta características clínicas particulares que la distinguen de la apendicitis aguda, tales como la presencia de dolor abdominal insidioso o intermitente y/o ausencia de sintomatología gastrointestinal (náuseas, vómitos o anorexia). En la diverticulitis apendicular las técnicas imagenológicas son de utilidad limitada al otorgar información inespecífica, por lo que el diagnóstico tiende a realizarse mediante el estudio anatomopatológico del apéndice posterior a una intervención quirúrgica en paciente con cuadro clínico compatible con apendicitis aguda. El tratamiento de elección corresponde a la apendicectomía, lo que permite evitar complicaciones futuras como por ejemplo perforación apendicular, neoplasias, entre otros. Se obtuvieron los datos de fuentes como Pubmed y Scielo. Específicamente la búsqueda de artículos originales y de revisiones sistemáticas, preferentemente menores a 15 años de publicación en revistas científicas de alto índice de impacto, con las palabras "diverticulitis apendicular", "diverticulosis" y "complicaciones diverticulares".

Appendiceal diverticulitis is a rare disease with an incidence of approximately 1%. It is defined by the presence of true or false diverticula in the wall of the cecal appendix. During the acute phase, it has symptoms that are indistinguishable from appendicitis, however, it sometimes presents particular clinical characteristics that distinguish it from acute appendicitis, such as the presence of insidious or intermittent abdominal pain and/or the absence of gastrointestinal symptoms (nausea, vomiting, or anorexia). In appendiceal diverticulitis, imaging techniques are of limited utility as they provide non-specific information, so the diagnosis tends to be made through the pathology study of the treatment after surgery in a patient with a clinical picture compatible with acute appendicitis. The treatment of choice corresponds to appendectomy, which allows avoiding future complications such as appendiceal perforation, neoplasms, among others. Data were obtained from sources such as Pubmed and Scielo, specifically searching for original articles and systematic reviews with the words "apendicular diverticulitis", "diverticulosis" and "diverticular complications". The criteria used were articles mainly under 5 years of publication in high-impact scientific journals.

Activation of cyclic AMP-dependent kinase is required but may not be sufficient to mimic cyclic AMP-dependent DNA synthesis and thyroglobulin expression in dog thyroid cells.

Thyrotropin (TSH), via a cyclic AMP (cAMP)-dependent pathway, induces cytoplasmic retractions, proliferation, and differentiation expression in dog thyroid cells. The role of cAMP-dependent protein kinase (PKA) in the induction of these events was assessed by microinjection into living cells. Microinjection of the heat-stable inhibitor of PKA (PKI) inhibited the effects of TSH, demonstrating that activation of PKA was required in this process. Overexpression of the catalytic (C) subunit of PKA brought about by microinjection of the expression plasmid pC alpha ev or of purified C subunit itself was sufficient to mimic the cAMP-dependent cytoplasmic changes and thyroperoxidase mRNA expression but not to induce DNA synthesis and thyroglobulin (Tg) expression. The cAMP-dependent morphological effect was not observed when C subunit was coinjected with the regulatory subunit (RI or RII subunit) of PKA. To mimic the cAMP-induced PKA dissociation into free C and R subunits, the C subunit was coinjected with the regulation-deficient truncated RI subunit (RIdelta1-95) or with wild-type RI or native RII subunits, followed by incubation with TSH at a concentration too low to stimulate the cAMP-dependent events by itself. Although the cAMP-dependent morphology changes were still observed, neither DNA synthesis nor Tg expression was stimulated in these cells. Taken together, these data suggest that in addition to PKA activation, another cAMP-dependent mechanism could exist and play an important role in the transduction of the cAMP signal in thyroid cells.

Tratamientos de primera línea para pacientes estadio IV con adenocarcinoma pulmonar de mutación EGFR / First-line treatments for stage IV patients with EGFR-mutated lung adenocarcinoma

Lung cancer is one of the leading causes of death in the world. Current treatments act directly on the signal transduction pathways in cancer cells, mainly. One of the main pathways is associated with the Epidermal Growth Factor (EGFR), whose mutations leads to uncontrolled cell proliferation and a higher rate of cell invasion. Activating mutations in the EGFR gene, which includes deletions in exon 19 and the L858R mutation in exon 21, were detected in most patients with non-small cell lung cancer (NSCLC). Studies of EGFR tyrosine kinase inhibitors (EGFR-TKIs) such as Gefitinib, Erlotinib and Afatinib, compared with platinum-based treatments, showed that EGFR-TKIs produce increased disease-free survival, although only in patients whose cancers harbor activating mutations in the EGFR gene. Clinical trials also demonstrated that EGFR-TKIs are effective as first-line therapies in stage IV pulmonary adenocarcinoma. Here, the main aspects of the activation of the EGFR pathway in NSCLC will be reviewed, highlighting the importance for health professionals of correctly identifying activating mutations in the EGFR gene and acting quickly at the molecular level based on aforementioned treatments. (AU)

Calretinin in rat ovary: an in situ hybridization and immunohistochemical study.

Calretinin is a cytosolic calcium-binding protein of the calmodulin superfamily, with high homology with calbindin D28k. The only cells in which calretinin has been described so far are neurons, in the central nervous system and in retina. In the present work, we describe the expression of the calretinin gene in the interstitial cells of rat ovary. Immunohistochemistry, using a calretinin-specific antibody, allowed to detect the protein from 19 days after birth. Western blot from ovary homogenates confirmed the labelling of a 29 kDa band, the size of calretinin. In situ hybridization confirmed immunochemical data; calretinin transcripts were clearly shown in the same cell population. This represents the first description of calretinin outside the nervous system. Its function in ovary remains to be determined.

Calbindin localization in African giant rat kidney (Cricetomys gambianus).

Cricetomys gambianus are rodents living in savanna and follow area. They can live with restricted drinking water eating fresh food. Therefore their kidney may have some adaptive mechanisms for ion/water homeostasis compared to usual laboratory rats. In this study we have looked for calbindin, an intracellular calcium binding protein previously found in distal convoluted tubules from all mammalian species that have been studied and able to increase, in vitro, Ca2+ reabsorption. We have shown by using in situ hybridization, immunoblotting and immunohistochemistry that calbindin was expressed in three different portions of the distal nephron of the African giant rat. Calbindin was found in distal convoluted tubules, in cortical collecting tubules and in outer medullary collecting ducts. By contrast, in laboratory rat, calbindin was only found in distal convoluted tubules and undetectable in medullary collecting ducts. Thick ascending limb of Henle's loop were calbindin negative as shown by double immunolabelling using anti-uromucoid (Tamm-Horsfall protein). As previously shown in laboratory rat and rabbit, transcellular Ca2+ movement seems to be facilitated by calbindin in renal tubules segments predominantly actively transporting Ca2+, it may be suggested that in African giant rat, outer medullary collecting ducts may also actively transport Ca2+. As calretinin, another intracellular calcium binding protein highly homologous to calbindin but whose function is still conjectural has been suspected to be expressed in kidney, we have looked and not found any calretinin in both adult rat species.

Structural organization of the 5' region of the thyroglobulin gene. Evidence for intron loss and "exonization" during evolution.

More than one third of thyroglobulin (1190 residues out of 2750) is made of one peptide motif repeated ten times in tandem. Segments unrelated to the motif interrupt this structure at various places. The corresponding gene region, which extends over 40 x 10(3) bases, was studied in detail. All exon borders and exon/intron junctions were localized precisely and sequenced, and their positions were correlated with the repetitive organization of the protein. When intron positions were compiled on a consensus sequence of all repeats, three categories of introns were observed. Except between repeats numbers 5 and 6, an intron was invariably found within the Cys codon making the limit of each motif. This category of intron most probably reflects the serial duplication events responsible for the evolution of this region of the gene. All other introns, except no. 2, are found at positions were the repetitive structure is disrupted by "inserted" peptides. We present the hypothesis that this second category of introns was already present in the original unit before the first duplication. Thereafter, they would have experienced either complete loss (some units do not contain any intron) or partial or total exonization, resulting in the slipping of intronic material into coding sequence. Intron no. 2, finally, separates motif no. 1 at a position on the boundary between two segments presenting sequence homology. This last type of intron probably reflects an initial duplication event at the origin of a primordial thyroglobulin gene motif. With all these characteristics, the thyroglobulin gene is presented as a paradigm for the analysis of the fate of introns in gene evolution.

Structure of chick chromosomal genes for calbindin and calretinin.

The chick chromosomal gene for calbindin (the 28,000 Mr intestinal calcium-binding protein) was cloned, and all the exons and flanking regions were sequenced. The promoter region contains typical ATAAA and GGGCGG boxes, the latter being unusual in "non-housekeeping" genes. Three polyadenylation signals are found in the calbindin gene that correspond to the three known mRNAs. Transcription termination is not efficient because homology with consensus sequences found downstream from the polyadenylation signal is weak. There are ten introns, most of which do not fall at homologous positions, neither with respect to the sixfold repeating structure of the calbindin protein, nor with respect to previously sequenced genes for calmodulin and other calcium-binding proteins. The gene for the related protein calretinin was cloned and partially sequenced. The introns are in the same positions in the calretinin and calbindin genes. The introns have apparently been inserted during the divergence of the calcium-binding protein superfamily.

Thyroperoxidase mRNA in quiescent and proliferating thyroid epithelial cells: expression and subcellular localization studied by in situ hybridization.

Using in situ hybridization procedure, we have investigated the regulation and the cellular localization of thyroperoxidase (TPO) messenger RNA accumulation as a marker of differentiation in dog thyroid epithelial cells in primary culture. The response to different mitogens (TSH acting through cAMP, EGF and TPA) has been compared. TPO mRNA accumulation was exquisitely dependent on a continuous TSH/cAMP stimulation. It was induced within 1 h in the whole cell population from a very low basal level. This effect was inhibited by the cAMP-independent mitogens EGF and TPA. By contrast, the TSH-induction of TPO mRNA accumulation was observed irrespectively of the proliferative activity of the cells, i.e. in the presence or the absence of insulin, which is required for mitogenesis. The short half-life of TPO mRNA (+/- 2 h) implies that it was continuously transcribed during TSH/cAMP-dependent cell cycling. As compared to another thyroid differentiation marker, thyroglobulin mRNA (Pohl et al., J. Cell Biol. 111, 663-672 (1990)), TPO mRNA accumulation differed by the rapidity of its control by cAMP, the pattern of its intercellular heterogeneity, and the unexpected segregation to a perinuclear region, probably the nuclear envelope that constitutes a specialized part of the endoplasmic reticulum. Despite these differences, both TPO and thyroglobulin gene transcriptions are unequivocally compatible with the cell cycle when induced by cAMP, at variance with the generally observed antagonism between growth and differentiation expression.

Expression of thyrotropin receptor (TSH-R), thyroglobulin, thyroperoxidase, and calcitonin messenger ribonucleic acids in thyroid carcinomas: evidence of TSH-R gene transcript in medullary histotype.

We studied the expression of the TSH receptor (TSH-R), thyroglobulin (Tg), thyroperoxidase (TPO), and calcitonin (CT) genes in a total of 53 tissues from 30 patients with thyroid carcinoma and from 9 patients with benign thyroid diseases. By Northern blot analysis of total RNA preparations, CT mRNA was expressed in all cases (n = 6) of medullary thyroid carcinoma (MTC). Surprisingly, 3 of them expressed the TSH-R mRNA, in association with the Tg and TPO mRNAs in 1. The presence of the TSH-R transcript in the neoplastic C-cells was confirmed in 1 MTC by in situ hybridization using a mixture of 3 oligonucleotide probes derived from dog TSH-R cDNA. With various degrees of expression, all differentiated thyroid carcinomas (20 papillary and 2 follicular) expressed TSH-R, Tg, and TPO, but not CT mRNAs. On the contrary, samples from 2 patients with anaplastic carcinoma did not express TSH-R, Tg, or TPO mRNA, but 1 of them expressed CT mRNA. All of the transcripts obtained from thyroid carcinomas (both primary and metastatic) were of the same size as the transcripts from normal or benign thyroid tissues, with the exception of 2 cases of differentiated thyroid cancer, in which TSH-R mRNA of lower mol wt (approximately 4.0 kilobases) was found in the absence of alteration in cDNA size and restriction map. The main conclusions of our study are that 1) the TSH-R gene is expressed in some MTC, which supports, at molecular level, the hypothesis of the existence of mixed follicular-medullary thyroid tumors; and 2) the expression of TSH-R, Tg, and TPO in undifferentiated thyroid cancer is lost.

Normal level of thyroglobulin messenger ribonucleic acid in a human congenital goiter with thyroglobulin deficiency.

Two siblings with congenital goiter were investigated from clinical, biochemical, and molecular biology standpoints. The association of clinical and biological hypothyroidism with undetectable levels of serum thyroglobulin (Tg) and the presence of iodohistidines in the urine suggested the diagnosis of defective Tg gene expression. This conclusion was confirmed by analysis of proteins present in goiter extracts. Only minute amounts of Tg-related material was detected by RIA (0.28 and 0.17 mg/g tissue compared to 80-100 mg/g in normal thyroid tissue), by Sepharose 6B chromatography, and by sucrose density gradient centrifugation. Surprisingly, the goiters contained normal amounts of Tg mRNA. The size of the mRNA and the sequence organization of its first five exons also were normal. We conclude that no gross alteration of structure or transcription of the Tg gene was present in these patients. The results are compatible with a lesion affecting the mRNA sequence (point mutation, splicing error etc.), leading to defective translation or abnormal routing of the translation product through the membrane system of the cell. This latter hypothesis is supported by the extreme distension of the goiter endoplasmic reticulum found on electron microscopy.

Electrical analogs for monitoring vascular properties in artificial heart studies.

The problem of choosing parametric descriptions of the systemic vascular bed suitable for monitoring beat-to-beat changes in peripheral vascular properties is considered. Three simple models with two, three, and five elements are compared, essentially exploiting the Akaike information criterion combined with reasonable requirements for estimate accuracy. Analysis of pressure data, which are either simulated by the five-element model or measured on a mock circulatory system during abrupt changes in peripheral resistance, suggests guidelines for model selection. In particular, the five-element model exhibits very close adherence to physical reality by allowing for reflection, while the classical windkessel model provides the most reproducible estimates.

Tracking time-varying properties of the systemic vascular bed.

The problem of tracking changes in viscoelastic properties of the systemic arterial bed is considered and a recursive estimation procedure, belonging to the class of output-error algorithms with adjustable compensator, is developed and discussed. By means of computer simulations, suitable values are determined for the key design variable which controls the tradeoff between tracking ability and noise sensitivity of the algorithm. In this way, the algorithm allows on-line estimation of arterial compliance, peripheral resistance, and characteristic impedance on the basis of aortic pressure and flow signals. Furthermore, the results obtained from data numerically simulated, as well as measured on a mock circulatory system, demonstrate that the dominant arterial time-constant can be tracked by the algorithm using only measurements of the aortic pressure during diastole.

Calbindin-D28 in mammalian brain, retina, and endocrine pancreas: immunohistochemical comparison with calretinin.

Calbindin 28K and calretinin are very similar calcium binding proteins which are both present in the central nervous system (CNS). They respectively bind 4 and 5 Ca++ ions. We have compared by immunohistochemistry and in situ hybridization their localisation in the brain and the retina. The two proteins are generally expressed in different neurons with a few neurons containing both calcium binding proteins. Calbindin 28K is also present in the endocrine system. We have examined the cellular distribution of calbindin in the pancreatic endocrine cells of chick, rat and human and found variable distribution among the different endocrine cell types. We also describe the presence of calbindin in RINm5F cells, an insulin-producing tumor cell line derived from a radiation-induced rat insulinoma.

[Structure and expression of thyroglobulin gene]. / Structure et expression du gène de la thyroglobuline.

Thyroglobulin is composed of two 300000 dalton polypeptide chains, translated from an 8000 base mRNA. Preparation of a full length cDNA and its cloning in E. coli have lead to the demonstration that the polypeptides of thyroglobulin protomers were identical. Used as molecular probes, the cloned cDNA allowed the isolation of a fragment of thyroglobulin gene. Electron microscopic studies have demonstrated that this gene contains more than 90% intronic material separating small size exons (less than 200 bp). Sequencing of bovine thyroglobulin structural gene is in progress. Preliminary results show evidence for the existence of repetitive segments. Availability of cloned DNA complementary to bovine and human thyroglobulin mRNA allows the study of genetic defects of thyroglobulin gene expression in the human and in various animal models.

[Ileus after appendicitis in children]. / Ileus po apendicitíde u detí.

A relatively frequent and alarming complication of appendicitis in children is ileus. The authors submit an analysis of 41 cases of ileus with a time interval of 3 days to 8 years after appendectomy. In eight patients conservative treatment was successful, and 33 children were operated with the finding of intraabdominal adhesions (23 times), bands (3 times), abscesses and adhesions (7 times). Two children were re-operated on account a relapsing ileus. None of the children died. Prophylaxis of ileus after appendectomy is ineffective and uncertain, therefore the authors emphasize early diagnosis and early operation of the appendicitis but warn against inadequately considered appendectomy.

Meloxicam associado ou não ao tramadol no controle da dor após ovário-histerectomia videoassistida em cadelas / Meloxican with or without tramadol for control of pain undergoing laparoscopic-assisted ovariohysterectomy in bitches

O objetivo deste estudo foi avaliar a eficácia do meloxicam associado ou não ao tramadol, no controle da dor após ovário-histerectomia (OVH) laparoscópica com dois portais. Foram selecionadas 14 cadelas hígidas. Os animais foram separados de forma aleatória, em dois grupos. O grupo M (GM) recebeu meloxicam (0,2mg kg-1, s.i.d.), enquanto os animais do grupo MT (GMT) receberam a associação de meloxicam (0,2mg kg-1, s.i.d.) e tramadol (4mg kg-1, t.i.d.), ambos durante dois dias de pós-operatório. Para avaliação da dor pós-cirúrgica, foram utilizadas as escalas de Melbourne e escala visual analógica (EVA), além de mensurações de glicemia e cortisol sérico. Não houve diferença ao se avaliarem os grupos GM e GMT pela escala de Melbourne nem pela EVA. As mensurações de cortisol não atingiram valores superiores aos de referência para a espécie, enquanto os valores de glicemia não apresentaram variação significativa ao longo do tempo de avaliação nem entre grupos. Com os resultados deste estudo, foi possível concluir que a utilização de meloxicam associado ou não ao tramadol, nas doses e posologias propostas, é eficaz para controlar a dor pós-operatória de cadelas submetidas à OVH laparoscópica com dois portais.

The aim of this study was to evaluate the efficacy of meloxicam with or without tramadol for pain control after laparoscopic-assisted ovariohysterectomy (OVH) by two-portal access. Were selected 14 healthy dogs to perform video-assisted OVHs. The animals were divided randomly into two groups (GM and GMT). The GM group received meloxicam (0.2mg kg-1, s.i.d), whereas the GMT group received the combination of meloxicam (0.2mg kg-1, s.i.d) and tramadol (4mg kg-1, tid), both for two days after surgery. To evaluate the post-surgical pain Melbourne and EVA scales were used, and blood glucose and serum cortisol were measured. There was no statistical difference when evaluating GM and GMT groups and the Melbourne scale or the visual analogue scale VAS. Cortisol measurements did not reach values higher than the reference for the species, while blood glucose levels did not present significant statistical variation throughout the evaluation time or between groups. With these results, we concluded that the use of meloxicam with or without the tramadol at the doses and dosage schedules proposed, is effective to control postoperative pain in bitches that had undergone video-assisted OVH with two-portal access.